LAUSR

The Kamlet and Taft solvent basicity parameter, β, and solvent polarity/polarizability parameter, π*, were analyzed in terms of properties of the solvent molecules derived from computational chemistry. The analysis of β, using a larger data set, confirms earlier conclusions that, for aprotic solvents, the basicity is determined by the partial charge on the most negative atom of the solvent molecule and by the energy of the highest energy molecular orbital associated with the donor site. For alcohols and nitrogen bases containing N–H moieties, the β values deviate systematically from those for the non-hydrogen bonding solvents. Analysis of the polarity/polarizability parameter, π*, shows that it depends directly on the dipole moment, and quadrupolar amplitude of the solvent and on the energy of the highest occupied molecular orbital, but decreases linearly with increasing solvent polarizability.